Brake



W. L. KRIEG Oct. 31, 1933.

BRAK E Filed March 1'7, 1930 F/GIZ m6 NE "MR mK L R E U M A TTORNEY Patented Oct. 31, 1933 UNITED STATES PATENT 11;;-

Bendix Aviation Corporation,

South Bend,

Ind, a corporation of Delaware Application March 17, 1930. Serial No. 436,308

8 Claims.

This invention relates to brakes and more particularly to internal expanding brakes.

A major object of the invention is to provide smoothness in operation of the brake.

An important object of the invention is to provide a simplified means for actuating the braking elements. I

Another object of the invention is to improve the structure of the parts and more particularly the structure of the parts for actuating the braking elements.

A further object of the invention is to provide means for actuating the brake shoes whereby the primary shoe may be moved for engagement with the drum slightly in advance of the secondary shoe.

With these and other objects in view which may be instant to my improvements, the invention consists in parts and combinations to be hereinafter set forth and claimed, with the understanding that the several elements constituting the invention may be varied in construction, proportion and arrangement without departing from the spirit and scope of the appended claims.

In order to make the invention more clearly understood, I have shown in the accompanying drawing, meansfor carrying the same into practical efiect without limiting the improvements in their useful application to the particular construction which for the purpose of illustration have been made the subject of illustration.

In the drawing which forms a part of this specification,

Figure 1 is a side elevation of a brake embodying the invention; 7

Figure 2 is a sectional View substantially on line 2--2, Figure 1;

Figure 3 is a sectional view substantially on line 33, Figure 1; and

Figure 4 is a diagrammatical view illustrating the movement of the toggle.

In the embodiment illustrated, there is provided a conventional rotatable drum It) at the open side of which is a stationary support such as a backing plate 11. Positioned on the backing plate are anchor pins 12 and 13 and steady rests 14 and 15. A primary shoe 16 is positioned on the steady rest 14 and is pivotally connected by a pin 17 to a secondary shoe 18 positioned on the anchor pin 12 and an auxiliary shoe 19 is positioned on the anchor pin 13 and steady rest 15. The primary shoe 16 and the auxiliary shoe 19 are provided with shouldered portionsZO and,

21 arranged in spaced relation with respect to each other.

These shoes are of a conventional type each having a run 22 to which is secured a suitable lining 23 adapted to engage the drum and a web 24, lending strength and rigidity to the rim. The primary and auxiliary shoes are each connected by a coil spring 25 to suitable fixed supports 26. These springs are commonly known as return springs and serve to maintain the shoes when in an ofi position, in proper spaced relation to the drum. As shown, the secondary shoe is con- 5 nected adjacent the articulating pin by a return spring 27 to a fixed support 28. The structure I hereinabove described is conventional and it is 'to be understood that other forms of brakes may be effectively employed in conjunction with the 7 present invention.

Positioned intermediate the shoulders 23 and 21 on the primary and auxiliary shoes is a stud 29 suitably secured to the backing plate as by a nut 30. The stud 29 has a reduced end portion 31 and a diainetral bore to receive a cotter pin 32, the object of which will be hereinafter explained. Positioned on the backing plate is a fixed support 33. As shown, this support has a conical shaped body portion provided with a shoulder 34 projecting through an aperture in the backing plate and secured thereto in any desirable manner tending to impart strength and rigidity to the support.

The support 33 is axially bored, as indicated at 35, to receive a shaft 36 having secured on the respective ends thereof arms 37 and 38 so positioned as to form a bell crank lever. Oneend of this bell crank lever is suitably connected to an operating cable, not shown, and the other end of the bell crank lever is connected to a toggle 39 comprising corresponding arms 40 and 41 suitably pivoted to the arm 3'7, as indicated at 42.

The arms 40 and ll are preferably arcuate and are arranged in overlapping relation. The overlapping portions are slotted as indicated at 43 and 44 to receive the reduced portion 31 on the stud 29 on which. they are suitably secured by the cotter pin 32. The free ends of the arms 10c 40 and 41 are preferably rounded and are adapted to engage the shoulders 20 and 21 on the primary and auxiliary shoes.

In operation, a pull on the operating cable moves thebell crank lever through an are which raises the toggle 39and causes the arms 40 and 41 to engage theshoulders 2e and 21 onthe primary and auxiliary shoes with sufficient force to spread the shoes for engagement with the drum. It should be noted, however, that by no reason of the arc through which the bell crank lever moves, greater movement is imparted to the arm 41 which engages the shoulder 21 on the primary shoe 16. Accordingly, the primary shoe is moved for engagement with the drum slightly in advance of the auxiliary shoe and it is well established that this action is highly desirable in a brake of the servo type.

Although this invention has been described in connection with certain specific embodiments, the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described the various features of the invention, what I claim is new and desire to secure by Letters Patent is:

1. A brake comprising braking elements and means for applying the braking elements including a toggle having overlapping legs and a bell crank lever for operating the toggle.

2. A brake comprising braking elements, means for actuating the braking elements including a toggle having curved overlapping legs and means for actuating the toggle whereby greater movement is imparted to one of the braking elements than to the other.

3. A brake comprising a drum, braking elements adaptable for co-operation therewith, means for applying the braking elements to the drum including a toggle having curved legs overlapping one another and means for actuating the toggle to apply one leg thereof to one of the braking elements in advance of applying the other braking elements.

4. A brake comprising a drum, braking elements adaptable for co-operation therewith, a toggle having arcuate overlapping legs for applying the braking elements to the drum and means for operating the toggle so that one leg will impart greater movement to one of the braking elements than to the other.

5. A brake comprising a drum, braking ele ments adaptable for co-operation with the drum, a toggle having corresponding legs arranged in overlapping position with their free ends engaging the respective braking elements and a bell crank lever pivotally connected to the toggle for spreading the respective ends thereof.

6. A brake comprising a drum, braking elements adaptable for co-operation with the drum, a toggle comprising corresponding overlapping legs arranged to slide one upon the other and means for operating the toggle including a bell crank lever.

'7. A brake comprising a drum, brake shoes adaptable for co-operation with the drum, a toggle for spreading the shoes for engagement with the drum comprising corresponding overlapping legs having rounded end portions engaging the respective shoes, means for slidably connecting the respective legs of the toggle and a bell crank lever for operating the toggle.

8. A brake comprising a rotatable drum, a fixed support associated with the drum, movable brake shoes positioned on the support adaptable for co-operation with the drum, a stud positioned intermediate the brake shoes, a toggle having corresponding overlapping legs provided with slots adapted to engage the stud intermediate the shoes, said toggle having rounded end portions engaging the shoulders on the respective shoes and a bell crank lever mounted on a fixed sup port and having one end pivotally connected to the toggle and the other end adapted for'connection to an operating cable.

WALTER L. KRIEG. 

